Here's the
official explanation provided by the GMAC for this question:
The first part of this sentence makes a general statement:
The medical profession is not in agreement about how to treat snakebites. The second part supports and explicates that statement in two ways: The first of these is about physicians’ uncertainty (they are
unsure), and the second is about medical professionals’ disagreement (
there is controversy). The sentence as originally presented uses two independent clauses in communicating the different nature of these two factors as well as their relationship to the generalization stated at the beginning of the sentence.
Option A: Correct. This is correct as explained above. This is structured in a way that clearly expresses how the two factors provide evidence of the lack of agreement in the medical profession, and how those two factors differ from each other.
Option B: The structure makes it unclear how the phrase
and have a controversy about is supposed to relate to the rest of the sentence. Syntactically, that phrase appears to be within the scope of
are not sure. It would be better to put this in an independent clause with its own subject or at least add a comma after
use. Also, the phrase
have a controversy about is unidiomatic and a little unclear.
Option C: They have controversy is unidiomatic.
Option D: This wording is awkward and indirect. The words
as to are unnecessary.
Option E: They have a controversy is unidiomatic and a little unclear. The phrase
as to what is is awkwardly wordy and indirect. The pronoun
what can be either singular or plural, depending on its context. Here it refers to the merits, so the verb should be plural instead of singular.
The correct answer is A.
Please note that I'm not the author of this explanation. I'm just posting it here since I believe it can help the community.